Convert remaining DATAPTR to DATAPTR_RO

[eddelbuettel]

As CRAN checks nag about the one remaining DAtAPTR use, a quick change to DATAPTR_RO which should pass for all reasonable use cases. Running full reverse-depends checks now (which will take its usual time ... measured in days now) to determine if anybody out there "is naughty" instead of nice.

Checklist

• Code compiles correctly
• R CMD check still passes all tests
• Preferably, new tests were added which fail without the change
• Document the changes by file in ChangeLog

[kevinushey]

LGTM!

[eddelbuettel]

🤞

Rev deps looking good too so far, but it's only been a fraction...

[kevinushey]

We probably need some way of eventually deprecating / removing this, but that feels like a "Later" kind of issue.

[eddelbuettel]

With the _RO being blessed, do we really have to?

[eddelbuettel]

No changes to worse or new issues. (A few packages added since last run had new depends, they will get re-tested in the next one I do for CLOENV (which is an 'empty' test as the condition will only for R 4.5.0 or later and we test with 4.4.*).

So merging.